/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2015 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.jpos.iso;

/**
 * Implements BCD Interpreter. Numeric Strings (consisting of chars '0'..'9' are converted
 * to and from BCD bytes. Thus, "1234" is converted into 2 bytes: 0x12, 0x34.
 *
 * @author joconnor
 * @version $Revision$ $Date$
 */
public class BCDInterpreter implements Interpreter {
	/**
	 * This BCDInterpreter sometimes adds a 0-nibble to the left.
	 */
	public static final BCDInterpreter LEFT_PADDED = new BCDInterpreter(true, false);
	/**
	 * This BCDInterpreter sometimes adds a 0-nibble to the right.
	 */
	public static final BCDInterpreter RIGHT_PADDED = new BCDInterpreter(false, false);
	/**
	 * This BCDInterpreter sometimes adds a F-nibble to the right.
	 */
	public static final BCDInterpreter RIGHT_PADDED_F = new BCDInterpreter(false, true);
	/**
	 * This BCDInterpreter sometimes adds a F-nibble to the left.
	 */
	public static final BCDInterpreter LEFT_PADDED_F = new BCDInterpreter(true, true);

	private boolean leftPadded;
	private boolean fPadded;

	/**
	 * Kept private. Only two instances are possible.
	 */
	private BCDInterpreter(boolean leftPadded, boolean fPadded) {
		this.leftPadded = leftPadded;
		this.fPadded = fPadded;
	}

	/**
	 * (non-Javadoc)
	 */
	public void interpret(String data, byte[] b, int offset) {
		ISOUtil.str2bcd(data, leftPadded, b, offset);
		// if (fPadded && !leftPadded && data.length()%2 == 1)
		//   b[b.length-1] |= (byte)(b[b.length-1] << 4) == 0 ? 0x0F : 0x00;
		int paddedSize = data.length() >> 1;
		if (fPadded && data.length() % 2 == 1)
			if (leftPadded)
				b[offset] |= (byte) 0xF0;
			else
				b[offset + paddedSize] |= (byte) 0x0F;
	}

	/**
	 * (non-Javadoc)
	 */
	public String uninterpret(byte[] rawData, int offset, int length) {
		return ISOUtil.bcd2str(rawData, offset, length, leftPadded);
	}

	/**
	 * Each numeric digit is packed into a nibble, so 2 digits per byte, plus the
	 * possibility of padding.
	 */
	public int getPackedLength(int nDataUnits) {
		return (nDataUnits + 1) / 2;
	}
}
